Tapped winding circulating air blower motors are used for air delivery in furnaces and the air delivery is factory matched for each speed tap for furnaces installed with or without an evaporator coil. Most installations, however, require modification of the factory settings to provide proper air delivery and this is done by changing the speed taps upon installation. Even if the motor speed is correct at installation, changes can occur within the system which require different motor settings to maintain the correct motor speed for the new conditions. These changed conditions can result from such causes as increased flow resistance due to dirty filters, closed ducts, reduced line voltage, and the increase in motor temperature. These changes cannot be controlled but they result in changes in the air delivery.